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  • new with exception with Microsoft

    - by wsd
    As I'm coding for both Windows and Linux, I have a whole host of problems. Microsoft Visual C++ has no stdint header, but for that I wrote my own. Now I found out that MS C++'s new operator does not throw an exception, so I want to fix this a quickly as possible. I know I can define a Macro with Parameters in Parenthesis, can I define a macro that replaces MyClass x = new MyClass(); with #ifdef MSC_VER if(!(MyClass x = new MyClass()) { throw new std::bad_alloc(); } #else MyClass x = new MyClass(); #endif (or something equivalent), AND works in BOTH MS C++ and G++ ? Or alternatively if that is not possible, a batch file to run over the Code to do this? I have become rather dependent on this exception being thrown.

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  • Does C++ have a static polymorphism implementation of interface that does not use vtable?

    - by gilbertc
    Does C++ have a proper implementation of interface that does not use vtable? for example class BaseInterface{ public: virtual void func() const = 0; } class BaseInterfaceImpl:public BaseInterface{ public: void func(){ std::cout<<"called."<<endl; } } BaseInterface* obj = new BaseInterfaceImpl(); obj->func(); the call to func at the last line goes to vtable to find the func ptr of BaseInterfaceImpl::func, but is there any C++ way to do that directly as the BaseInterfaceImpl is not subclassed from any other class besides the pure interface class BaseInterface? Thanks. Gil.

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  • What does the C++ compiler error "looks like a function definition, but there is no parameter list;"

    - by SkyBoxer
    #include <iostream> #include <fstream> using namespace std; int main { int num1, num2; ifstream infile; ostream outfile; infile.open("input.dat"); outfile.open("output.dat"); infile >> num 1 >> num 2; outfile << "Sum = " << num1 + num2 << endl; infile.close() outfile.close() return 0; } This is what I did and when I compile it, I got this error that said error C2470: 'main' : looks like a function definition, but there is no parameter list; skipping apparent body Please don't hate me :( I am new at this computer science....

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  • C++ Boost bind value type

    - by aaa
    hello. I look in documentation and source code but cannot figure out how to get return value type of boost bind functor. I am trying to accomplish following: 35 template<typename T,size_t N, class F> 36 boost::array<typename F::value_type, N> make_array(T (&input)[N], F unary) { 37 boost::array<typename F::value_type, N> array; 38 std::transform(input, input + N, array.begin(), unary); 39 return array; 40 } where F can be bind functor. the above does not work because functor does not have value_type. for that matter, is there standard interface for unary/binary functor as far as return value. Thanks

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  • C++ cin returns 0 for integer no matter what the user inputs

    - by kevin dappah
    No matter the cin it continues to to output 0 for score. Why is that? I tried returning the "return 0;" but still no go :/ #include "stdafx.h" #include <iostream> using namespace std; // Variables int enemiesKilled; const int KILLS = 150; int score = enemiesKilled * KILLS; int main() { cout << "How many enemies did you kill?" << endl; cin >> enemiesKilled; cout << "Your score: " << score << endl; return 0; }

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  • C++ SDL State Machine Segfault

    - by user1602079
    The code compiles and builds fine, but it immediately segfaults. I've looked at this for a while and have no idea why. Any help is appreciated. Thank you! Here's the code: main.cpp #include "SDL/SDL.h" #include "Globals.h" #include "Core.h" #include "GameStates.h" #include "Introduction.h" int main(int argc, char** args) { if(core.Initilize() == false) { SDL_Quit(); } while(core.desiredstate != core.Quit) { currentstate->EventHandling(); currentstate->Logic(); core.ChangeState(); currentstate->Render(); currentstate->Update(); } SDL_Quit(); } Core.h #ifndef CORE_H #define CORE_H #include "SDL/SDL.h" #include <string> class Core { public: SDL_Surface* Load(std::string filename); void ApplySurface(int X, int Y, SDL_Surface* source, SDL_Surface* destination); void SetState(int newstate); void ChangeState(); enum state { Intro, STATES_NULL, Quit }; int desiredstate, stateID; bool Initilize(); }; #endif Core.cpp #include "Core.h" #include "SDL/SDL.h" #include "Globals.h" #include "Introduction.h" #include <string> /* Initilizes SDL subsystems */ bool Core::Initilize() { //Inits subsystems, reutrns false upon error if(SDL_Init(SDL_INIT_EVERYTHING) == -1) { return false; } SDL_WM_SetCaption("Game", NULL); return true; } /* Loads surfaces and optimizes them */ SDL_Surface* Core::Load(std::string filename) { //The surface to be optimized SDL_Surface* original = SDL_LoadBMP(filename.c_str()); //The optimized surface SDL_Surface* optimized = NULL; //Optimizes the image if it loaded properly if(original != NULL) { optimized = SDL_DisplayFormat(original); SDL_FreeSurface(original); } else { //returns NULL upon error return NULL; } return optimized; } /* Blits surfaces */ void Core::ApplySurface(int X, int Y, SDL_Surface* source, SDL_Surface* destination) { //Stores the coordinates of the surface SDL_Rect offsets; offsets.x = X; offsets.y = Y; //Bits the surface if both surfaces are present if(source != NULL && destination != NULL) { SDL_BlitSurface(source, NULL, destination, &offsets); } } /* Sets desiredstate to newstate */ void Core::SetState(int newstate) { if(desiredstate != Quit) { desiredstate = newstate; } } /* Changes the game state */ void Core::ChangeState() { if(desiredstate != STATES_NULL && desiredstate != Quit) { delete currentstate; switch(desiredstate) { case Intro: currentstate = new Introduction(); break; } stateID = desiredstate; desiredstate = core.STATES_NULL; } } Globals.h #ifndef GLOBALS_H #define GLOBALS_H #include "SDL/SDL.h" #include "Core.h" #include "GameStates.h" extern SDL_Surface* screen; extern Core core; extern GameStates* currentstate; #endif Globals.cpp #include "Globals.h" #include "SDL/SDL.h" #include "GameStates.h" SDL_Surface* screen = SDL_SetVideoMode(640, 480, 32, SDL_SWSURFACE); Core core; GameStates* currentstate = NULL; GameStates.h #ifndef GAMESTATES_H #define GAMESTATES_H class GameStates { public: virtual void EventHandling() = 0; virtual void Logic() = 0; virtual void Render() = 0; virtual void Update() = 0; }; #endif Introduction.h #ifndef INTRODUCTION_H #define INTRODUCTION_H #include "GameStates.h" #include "Globals.h" class Introduction : public GameStates { public: Introduction(); private: void EventHandling(); void Logic(); void Render(); void Update(); ~Introduction(); SDL_Surface* test; }; #endif Introduction.cpp #include "SDL/SDL.h" #include "Core.h" #include "Globals.h" #include "Introduction.h" /* Loads all the assets */ Introduction::Introduction() { test = core.Load("test.bmp"); } void Introduction::EventHandling() { SDL_Event event; while(SDL_PollEvent(&event)) { switch(event.type) { case SDL_QUIT: core.SetState(core.Quit); break; } } } void Introduction::Logic() { //to be coded } void Introduction::Render() { core.ApplySurface(30, 30, test, screen); } void Introduction::Update() { SDL_Flip(screen); } Introduction::~Introduction() { SDL_FreeSurface(test); } Sorry if the formatting is a bit off... Having to put four spaces for it to be put into a code block offset it a bit. I ran it through gdb and this is what I got: Program received signal SIGSEGV, Segmentation fault. 0x0000000000400e46 in main () Which isn't incredibly useful... Any help is appreciated. Thank you!

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  • How to interrupt a waiting C++0x thread?

    - by doublep
    I'm considering to use C++0x threads in my application instead of Boost threads. However, I'm not sure how to reimplement what I have with standard C++0x threads since they don't seem to have an interrupt() method. My current setup is: a master thread that manages work; several worker threads that carry out master's commands. Workers call wait() on at least two different condition variables. Master has a "timed out" state: in this case it tells all workers to stop and give whatever result they got by then. With Boost threads master just uses interrupt_all() on a thread group, which causes workers to stop waiting. In case they are not waiting at the moment, master also sets a bool flag which workers check periodically. However, in C++0x std::thread I don't see any replacement for interrupt(). Do I miss something? If not, how can I implement the above scheme so that workers cannot just sleep forever?

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  • why this signal handler is called infinitely

    - by lz_prgmr
    I am using Mac OS 10.6.5, g++ 4.2.1. And meet problem with following code: #include <iostream> #include <sys/signal.h> using namespace std; void segfault_handler(int signum) { cout << "segfault caught!!!\n"; } int main() { signal(SIGSEGV, segfault_handler); int* p = 0; *p = 100; return 1; } It seems the segfault_handler is called infinitely and keep on print: segfault caught!!! segfault caught!!! segfault caught!!! ... I am new to Mac development, do you have any idea on what happened?

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  • Segfault when calling a method c++

    - by shuttle87
    I am fairly new to c++ and I am a bit stumped by this problem. I am trying to assign a variable from a call to a method in another class but it always segfaults. My code compiles with no warnings and I have checked that all variables are correct in gdb but the function call itself seems to cause a segfault. The code I am using is roughly like the following: class History{ public: bool test_history(); }; bool History::test_history(){ std::cout<<"test"; //this line never gets executed //more code goes in here return true; } class Game{ private: bool some_function(); public: History game_actions_history; bool local_variable; }; bool Game::some_function(){ local_variable = game_actions_history.test_history(); if (local_variable == true){ return true; } else{ return false; } } Any tips or advice is greatly appreciated!

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  • How To Parse String File Txt Into Array With C++

    - by Ibnu Syuhada
    I am trying to write a C++ program, but I am not familiar with C++. I have a .txt file, which contains values as follows: 0 0.0146484 0.0292969 0.0439453 0.0585938 0.0732422 0.0878906 What I have done in my C++ code is as follows: #include <iostream> #include <fstream> using namespace std; int main() { string line; ifstream myReadFile; myReadFile.open("Qi.txt"); if(myReadFile.is_open()) { while(myReadFile.good()) { getline(myReadFile,line); cout << line << endl; } myReadFile.close(); } return 0; } I would like to make the output of the program an array, i.e. line[0] = 0 line[1] = 0.0146484 line[2] = 0.0292969 line[3] = 0.0439453 line[4] = 0.0585938 line[5] = 0.0732422 line[6] = 0.0878906

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  • Shuffle array variables in a pre-specified order, without using extra memory of "size of input array"

    - by Eternal Learner
    Input : A[4] = {0,4,-1,1000} - Actual Array P[4] = {1,0,3,2} - Order to be reshuffled Output: A[4] = {4,0,1000,-1} Condition : Don't use an additional array as memory. Can use an extra variable or two. Problem : I have the below program in C++, but this fails for certain inputs of array P. #include<iostream> using namespace std; void swap(int *a_r,int *r) { int temp = *r; *r = *a_r; *a_r = temp; } int main() { int A[4] = {0,4,-1,1000}; int P[4] = {3,0,1,2}; int value = A[0] , dest = P[0]; for(int i=0; i<4;i++) { swap(&A[dest],&value); dest = P[dest]; } for(int i=0;i<4;i++) cout<<A[i]<<" "; }

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  • How to switch iostream from binary to text mode and vice versa?

    - by Mad Fish
    I want to read both formatted text and binary data from the same iostream. How can I do that? Why? Imagine this situation: You have different resources, and resource loaders for them, that take a std::istream as a parameter. And there are a "resource source" that provides these streams. Resources can be both text and binary and I need to handle both cases with resource loaders. Or other situation: Image that you have an archive with resources of mixed types. How can I get a text stream from inside the binary archive stream?

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  • C++: conjunction of binds?

    - by Helltone
    Suppose the following two functions: #include <iostream> #include <cstdlib> // atoi #include <cstring> // strcmp #include <boost/bind.hpp> bool match1(const char* a, const char* b) { return (strcmp(a, b) == 0); } bool match2(int a, const char* b) { return (atoi(b) == a); } Each of these functions takes two arguments, but can be transformed into a callable object that takes only one argument by using (std/boost)bind. Something along the lines of: boost::bind(match1, "a test"); boost::bind(match2, 42); I want to be able to obtain, from two functions like these that take one argument and return bool, a callable object that takes two arguments and returns the && of the bools. The type of the arguments is arbitrary. Something like an operator&& for functions that return bool.

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  • Why do I get the error "X is not a member of Y" even though X is a friend of Y?

    - by user1232138
    I am trying to write a binary tree. Why does the following code report error C2039, "'<<' : is not a member of 'btree<T'" even though the << operator has been declared as a friend function in the btree class? #include<iostream> using namespace std; template<class T> class btree { public: friend ostream& operator<<(ostream &,T); }; template<class T> ostream& btree<T>::operator<<(ostream &o,T s) { o<<s.i<<'\t'<<s.n; return o; }

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  • C++ Pointers to functions.

    - by Andy Leman
    using namespace std; int addition (int a, int b) { return (a+b); } int subtraction (int a, int b) { return (a-b); } int operation (int x, int y, int (*functocall)(int,int)) { int g; g = (*functocall)(x,y); return(g); } int main() { int m,n; int (*minus)(int,int) = subtraction; m = operation (7,5,addition); n = operation (20,m,minus); cout << n; return 0; } Can anybody explain this line for me int (*minus)(int,int) = subtraction; Thanks a lot!

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  • Possible for C++ template to check for a function's existence?

    - by andy
    Is it possible to write a C++ template that changes behavior depending on if a certain member function is defined on a class? Here's a simple example of what I would want to write: template<class T> std::string optionalToString(T* obj) { if (FUNCTION_EXISTS(T->toString)) return obj->toString(); else return "toString not defined"; } So if class T has "toString" defined then it uses it, otherwise it doesn't. The magical part that I don't know how to do is the "FUNCTION_EXISTS" part.

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  • Determine an object's class returned by a factory method (Error: function does not take 1 arguments

    - by tzippy
    I have a factorymethod that either returns an object of baseclass or one that is of derivedclass (a derived class of baseclass). The derived class has a method virtual void foo(int x) that takes one argument. baseclass however has virtual void foo() without an argument. In my code, a factory method returns a pointer of type bar that definetly points to an object of class derivedclass. However since this is only known at runtime I get a compiler error saying that foo() does not take an argument. Can I cast this pointer to a pointer of type derivedclass? std::auto_ptr<baseclass> bar = classfactory::CreateBar(); //returns object of class derivedclass bar->foo(5); class baseclass { public: virtual void foo(); } class derivedclass : public baseclass { public: virtual void foo(int x); }

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  • Using pow() for large number

    - by g4ur4v
    I am trying to solve a problem, a part of which requires me to calculate (2^n)%1000000007 , where n<=10^9. But my following code gives me output "0" even for input like n=99. Is there anyway other than having a loop which multilplies the output by 2 every time and finding the modulo every time (this is not I am looking for as this will be very slow for large numbers). #include<stdio.h> #include<math.h> #include<iostream> using namespace std; int main() { unsigned long long gaps,total; while(1) { cin>>gaps; total=(unsigned long long)powf(2,gaps)%1000000007; cout<<total<<endl; } }

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  • What is a good standard for code width?

    - by BillyONeal
    Hello everyone :) I've heard in several places that it's bad to have code that is too wide onscreen. For example: for (std::vector<EnumServiceInformation>::const_iterator currentService = services.begin(); currentService != services.end(); currentService++) However, I've heard many arguments for 80 character wide limits. I'm assuming this 80 character limit comes from the traditional command prompt, which is typically 80 characters wide. However -- most of us are working on something much better than a typical command prompt, and I feel that using an 80 character limit encourages use of variable names that are far too short and do not describe what the variable is used for. What is a reasonable limit for a new project with no existing coding width standard?

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  • Does C++ have a proper implementation of interface that does not use vtable?

    - by gilbertc
    Does C++ have a proper implementation of interface that does not use vtable? for example class BaseInterface{ public: virtual void func() const = 0; } class BaseInterfaceImpl:public BaseInterface{ public: void func(){ std::cout<<"called."<<endl; } } BaseInterface* obj = new BaseInterfaceImpl(); obj->func(); the call to func at the last line goes to vtable to find the func ptr of BaseInterfaceImpl::func, but is there any C++ way to do that directly as the BaseInterfaceImpl is not subclassed from any other class besides the pure interface class BaseInterface? Thanks. Gil.

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  • How do i use 'auto' in C++ (C++0x) ?

    - by LoudNPossiblyRight
    What do i have to do to this code to make it compile, it's braking around this line: auto val = what.getObject(); #include<iostream> using namespace std; class CUP{ public: void whatsHappening(){} }; class MUG{ public: void whatsHappening(){} }; class CupThrower{ public: CUP cp; CUP getObject(){ return cp;} }; class MugThrower{ public: MUG mg; MUG getObject(){return mg;} }; template <typename T> void whatsHappening(T what){ auto val = what.getObject(); //DOES NOT COMPILE val.whatsHappening(); } int main(){ CupThrower ct; MugThrower mt; whatsHappening(ct); whatsHappening(mt); return 0; } i am using VS2008 to compile.

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  • pointer delegate in STL set.

    - by ananth
    hi. Im kinda stuck with using a set with a pointer delegate. my code is as follows: void Graph::addNodes (NodeSet& nodes) { for (NodeSet::iterator pos = nodes.begin(); pos != nodes.end(); ++pos) { addNode(*pos); } } Here NodeSet is defined as: typedef std::set NodeSet; The above piece of code works perfectly on my windows machine, but when i run the same piece of code on a MAC, it gives me the following error: no matching function for call to 'Graph::addNode(const boost::shared_ptr&)' FYI, Node_ptr is of type: typedef boost::shared_ptr Node_ptr; can somebody plz tell me why this is happening?

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  • Convert a number from string to integer without using inbuilt function

    - by Raja
    I am trying this technique but error is coming. Please help me to convert a number from string to integer. #include<iostream> using namespace std; int main() { char *buffer[80]; int a; cout<<"enter the number"; cin.get(buffer,79); char *ptr[80] = &buffer; while(*ptr!='\0') { a=(a*10)+(*ptr-48); } cout<<"the value"<<a; delete ptr[]; return 0; } Errors are: error C2440: 'initializing' : cannot convert from 'char ()[80]' to 'char *[80]' error C2440: '=' : cannot convert from 'char *' to 'int'

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  • C++ a map to a 2 dimensional vector

    - by user1701545
    I want to create a C++ map where key is, say, int and value is a 2-D vector of double: map myMap; suppose I filled it and now I would like to update the second vector mapped by each key (for example divide each element by 2). How would I access that vector iteratively? The "itr-second[0]" syntax in the statement below is obviously wrong. What would be the right syntax for that action? for(std::map<in, vector<vector<double> > > itr = myMap.begin(); itr != myMap.end();++itr) { for(int i = 0;i < itr->second[0].size();++i) { itr->second[0][i] /= 2; } } thanks, rubi

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  • Modify input stream data on the fly

    - by Frizi
    I would like to implement a std::stream modifier/parser, that is doing data manipulation on the fly. Is it possible to create it in form of stream manipulator? For example, i want to strip all the line comments (from any // to the end of line) out of the stdin and pass it to stdout. string str; istream strippingCin = cin >> stripcomments; while(strippingCin.good()) { strippingCin >> str; cout << str; } There may be also a large file input instead of cin, so i don't want to load full stream data into memory at once. Is it possible without writing my own stream class? Maybe is there another route i should take instead?

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